[cairo] How do I use an XRender Picture as a Cairo surface?

[Bill Spitzak]

Actually try CAIRO_FILTER_BILINEAR, that is what XRender does

Currently if you use CAIRO_FILTER_GOOD then it triggers local image
drawing, which may be most of the problem, not the filtering. I have a
patch submitted to pixman to try to move the function there (and thus into
X) but it has not been accepted yet.


On Wed, Aug 19, 2015 at 11:18 AM, adlo <adloconwy at gmail.com> wrote:

> xfwm4's window previews seem to be scaled fast enough, and at a quality
> intermediate to that of CAIRO_FILTER_FAST and CAIRO_FILTER_GOOD. I suppose
> it uses XRender, but what could it be doing?
>
> Also, if I choose CAIRO_FILTER_GOOD, my previews do not update in response
> to X11 Damage events. If I use CAIRO_FILTER_FAST, it works properly. Why is
> this, and how could I resolve this?
>
> Regards
>
> adlo
>
>
>
> On 19 Aug 2015, at 01:52, Bill Spitzak <spitzak at gmail.com> wrote:
>
>
>
> On Tue, Aug 18, 2015 at 2:24 PM, adlo <adloconwy at gmail.com> wrote:
>
>> > On 18 Aug 2015, at 19:13, Uli Schlachter <psychon at znc.in> wrote:
>> >
>> > Why do you want to use a picture instead of directly using the drawable?
>>
>> I am writing a GTK2 program that gets previews/screenshots of all open
>> windows. My program scales the previews and puts them in GtkImages.
>>
>> CAIRO_FILTER_FAST gives rather low-quality results, but CAIRO_FILTER_GOOD
>> is rather slow.
>>
>> I wanted to try scaling the previews using XRender in order to find out
>> if it is any better or faster compared to Cairo scaling.
>>
>
> Unfortunatly XRender is going to give the the exact same results as
> CAIRO_FILTER_FAST.
>
>
>
>
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